Preventing leakage of current to studs in surface-contact systems of electric traction.



PATENTED SEPT. 8, 1903.

I H. BEDELL. PREVENTING LEAKAGE. 0F 01111135111: TO STUDS IN SURFACE CONTACT SYSTEMS OP ELECTRIC TRACTION.v

APPLICATION FILED MAR. 17. 1903.

N0 MODEL.

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1 UNITED STATES fatented September 8 1903.

PATENT FFICE.

BENJAMIN HARRY BEDE LL, OF LONDON, ENGLAND, ASSIGNOR OF NINE- TENTHS TO WILLIAM GRIFFITHS, LONDON, ENGLAND.

PREVENTING LEA KAGE OF CURRENT TO STUDS IN SURFACE-CONTACT SYSTEMS F ELECTRIC TRACTION.

SPECIFICATION forming part of Letters Patent No. 738,651 dated September 8, 1903.

Application filed March 17, 1903.

To all whom it may concern.-

Be it known that I, BENJAMIN HARRY BE- DELL, a subject of the King of Great Britain, residing at 41 and 42 Hamilton House,Bishops gate street Without, London, England, have invented new and useful Improvements in Preventing Leakage of Current toStuds in Surface-Contact Systems of Electric Traction of which the following is a specification.

This invention relates to improvements in preventing road-studs used in connection with surface-contact systems of electric traction from being alive due to leakage of current over the insulating-surfaces interposed between them and the cables, mains, or live terminals from which the electric energy is de rived for working the system. In most surface-contact systems as heretofore constructed such leakage of current has been found to be a great source of danger to horses and pedestrians; and itis the object of this invention to provide means for obviating this danger.

To this end the insulating-surface between the live conductor and the stud or parts normally in electrical connection therewithis completely intersected by a band of conducting material acrosswhich any leakage ourrent from the live conductor to the stud would be obliged to pass before it could reach the stud. This band is efficientlycon'nected to the rails or to earth direct, which insures all the leakage-current from the live conductor passing direct to earth without going'first to the stud, whereby it is impossible for the stud to be made or maintained alive by leakage from the live conductor, no matter how pernumber of roller-insulators c,rotatably mount ed upon pins d, held in the conduit 1), e being and thence direct to earth.

Serial No. 148,228. (No model.)

the flexible cable which is carried by the insulators 0. Now according to the invention the aforementioned strip of conducting material is' in this case formed by the pin d, and one end (1' of the said pin is extended through the conduit, as clearly shown, being connected at its end to an iron or other conducting strip f, which is earthed or connected to the rails. Bythis arrangement all leakage-current from the live cable 6 must pass through the pinbefore it can in any way reach the stud a, and as the said pin is earthed such current cannot under any circumstances obtain access to the said stud.

In Fig. 2 the stud a depends into a box g, which carries the switch device h in connection withthe live cable a. In this arrangement the conducting-band is in the form of the metal strip j, which divides the insulating-surface of the upper part of the box 9 into two parts. It is connected to earth by the wire is, passing from it through the box to an earth connection, so that any surface leakage from the contact h or other normally live parts cannot reach the stud a, since it must of necessity first pass through the strip The position of the earth-connected conducting-band upon the insulating-surface may vary in its relative position with respect to the normally live and normally dead parts between which it is desired to prevent leakage. It is usually preferred, however, to put it somewhat nearer to the normally dead parts than to the normally live parts, as shown in Fig. 2, as

.by this arrangement the total amount of leakage-current is reduced.

Having now particularly described and ascertained the nature of my saidinvention and in what manner the same is to be performed, I declare that what I claim i s- 1. In a surface-contact system of electric traction, the combination with a non conducting inclosure containing normally live parts and normally dead parts, of. an earthconnected conductor extending within. the inclosure in a position to intercept any leakage of current from the live parts to the dead parts, substantially as described.

2. In surface-contact systems of electric traction, the combination with the normally neath or adjacent to them, the combination 1 with the switch-box, of a strip or band of conducting material secured to the surface of the box between the two switch parts and connected to earth, substantially as hereinbefore described.

BENJAMIN HARRY BEDELL.

Witnesses:

O. G. REDFERN, JOHN E. BOUSFIELD. 

